The present invention relates to cold water soluble gelatin; and, particularly, to an improved cold water soluble gelatin product and a process for preparing it.
Gelatin is a widely used food ingredient. It has the ability to thicken or otherwise improve the texture of a variety of liquid products and also to set to a heat reversible gel which is useful in preparing products such as gelatin desserts. In products such as salad dressings, it aids in suspending particulate ingredients, and in frozen products such as ice cream it has the ability to retard the growth of ice crystals.
The art has long recognized a need for cold water soluble gelatin products. Unfortunately, it has been difficult until this time to achieve good solubility for gelatin in cold water. One area in particular where cold water solubility would be desirable is for the preparation of gelatin dessert mixes. There is a growing demand for all categories of food products which can be fully prepared and ready for consumption in the shortest period of time. The vast majority of gelatin dessert mixes which are currently available require the use of hot or boiling water to dissolve the gelatin and extended times, on the order of from about 2 to 4 hours, to permit them to achieve the proper consistency for eating. Thus, these products are often viewed as inconvenient because they require the use of hot or boiling water and also because of the extended setting time before they can be enjoyed. Because of this, many consumers who enoy eating gelatin desserts and salads prepared with them forego their use because they perceive them as too inconvenient.
This problem was recognized by Hagerty in U.S. Pat. No. 2,803,548 wherein he disclosed that a room-temperature soluble gelatin could be prepared by drying a gelatin solution at reduced pressure within a relatively narrow temperature range of between 37.degree. and 70.degree. C. According to his procedure, an aqueous gelatin solution, preferably containing a sugar such as sucrose, was first prepared by heating and was then dried at the indicated temperatures at pressures of from 50 to 100 millimeters of mercury. The disclosure emphasizes the need to dry at the indicated temperatures at pressures of from 50 to 100 millimeters of mercury. The disclosure emphasizes the need to dry at the indicated temperatures and states where dextrose or corn syrup are substituted for the sucrose, a dense, rather than fluffy, product is produced. While the patent suggests that the material is soluble in cold water, no specific details as to water temperature or time for solution are given. The patent does indicate, however, that gel strength of products prepared according to the disclosure are about 10% less than those prepared by conventional techniques.
In U.S. Pat. No. 2,948,622, Cahn discloses that a hot solution comprising about one part gelatin, nine parts sugar and 10 parts water can be dried as a thin film, and that the dry product is soluble in cold tap water. Contrary to the disclosure of Hagerty, Cahn indicates that the temperature should be between 70.degree. and 120.degree. C. and the pressure should be near atmospheric. He indicates, however, that pressures down to about 0.75 atmospheres can also be employed. While the exact conditions of dissolution of the final product in cold water are not given, it is indicated that the product of at least one example can be dissolved in cold water and then fully set by cooling for about 45 minutes at a temperature of 10.degree. C.
In addition to the batch drying process of Hagerty and the atmospheric drum drying process of Cahn, these two workers together disclosed in U.S. Pat. No. 2,841,498 that a cold water soluble gelatin could be prepared by spray drying an aqueous solution of sucrose and gelatin, provided that the sucrose content was at least 8 times, and preferably on the order of 9 or 10 times, the gelatin content. This disclosure is very specific as to the need for sugar to be sucrose and that the sucrose be present in a specific concentration. While other sugars such as dextrose and corn syrup solids are disclosed, they are mentioned only for admixture with the spray dried product. Cahn and Hagerty disclose that after dissolving their product in cold water, it sets to a gel within between about 7 to 15 minutes when cooled to about 32.degree. F., and a solution at 75.degree. F. when placed in an ordinary kitchen refrigerator sets to a firm gel therein in about one and one-half hours. It is disclosed that the acid component can be included prior to drying if desired.
In Canadian Pat. No. 896,965 to de Boer and U.S. Pat. No. 3,904,771 to Donnelly et al, there are described procedures for preparing various cold water soluble gelatin products by spray drying solutions comprising gelatin and an acid. Donnelly et al disclose that in addition to the acid which is employed at a level of from about 30 to 200% by weight of gelatin, the solution can contain a sugar such as fructose or sucrose prior to spray drying. In the Canadian patent, however, de Boer indicates that sugar can be eliminated from the spray drying solution where the acid is employed at a level of from about 5 to about 20% based upon the weight of the gelatin. According to de Boer, spray drying the dilutely acid gelatin solution permits the formation of fine droplets for enhanced drying.
According to the disclosure of Kalafatas in U.S. Pat. No. 3,927,221, the need for elaborate or extensive drying systems of the type described in U.S. Pat. Nos. 2,803,548, 2,841,498 and 2,948,622 can be obviated by the use of an extrusion process. According to this disclosure, the cold water soluble gelatin composition is prepared by subjecting a sugar/gelatin admixture to heat and pressure while applying shearing forces to the admixture in an extruder. The products are said to dissolve in water at about 50.degree. F. after 2 minutes of spoon stirring. The solutions prepared in this manner are set after about two hours refrigeration, as compared to about four hours when hot water is used to dissolve conventional gelatin dessert mixes. The disclosure incidentally mentions the use of dispersants, wetting agents and emulsifiers to enhance dispersibility. Similarly, U.S. Pat. No. 2,819,970 to Steigmann and U.S. Pat. No. 2,819,971 to Gunthardt also mention the use of additives of this type.
Recently issued U.S. Pat. Nos. 4,401,685; 4,407,836; and 4,409,255 describe processes for the preparation of cold water soluble gelatins which possess markedly improved properties as compared with those previously known in the art. These patents all call for the use of a particular sugar composition, namely a mixture of corn syrup solids and maltodextrin, in combination with gelatin in a range of ratio of sugar to gelatin by weight of 2:1 to 12:1 preferably 3-7:1. An aqueous solution is prepared containing the gelatin, sugar, an acid and a surfactant and the solution is dried. In the '685 patent, the drying is effected by spreading a thin layer of the solution on a surface heated with steam at 10-60 psig pressure. In the '836 patent, the solution is extruded as a foam and then dried.
It has now been found that cold water soluble gelatins having even more enhanced properties can be obtained by a modification of the processes described in the latter three patents set forth above, which modification is described in detail below.